Temporal expression of herpes simplex virus type 1 mRNA in murine retina

Purpose. During maturation of herpes simplex virus type I (HSV) in infected murine retinal F strain ganglion cells, new viral components are axonally transported in two phases. The viral envelope protein (gD) appears 48 hr before the capsid protein (VP5). Our hypothesis was that delayed appearance of VP5 mRNA in the infected eye causes the delayed expression of the VP5 protein in the axon. Methods. HSV was injected into the ocular posterior chamber. Three to 24 hr later, the mice were euthanized, and the posterior eye was isolated. RNA was extracted, DNAase-treated, and used for amplification by reverse transcription-polymerase chain reaction (RT-PCR) using primers specific to gD, VP5 and a tegument protein VP22. Results. VP22 and gD mRNAs are expressed 6 hr and VP5 mRNA is first detected 9 hr after infection. Conclusions. The results establish that delayed transcription does not play a significant role in the 48-hr delay in VP5 appearance in the retinal axons.